libdsp: update LP_FILTER comment

add note about filter time constant (tau)
2023-10-19 12:14:45 +02:00 · 2023-10-19 12:14:45 +02:00 · 93312c6196
parent c164fc9b21
commit 93312c6196
2 changed files with 2 additions and 0 deletions
--- a/include/dsp.h
+++ b/include/dsp.h
@ -102,6 +102,7 @@
 *     filter = T * (2*PI) * f_c
 *
 *     phase shift = -arctan(f_in/f_c)
+ *     time constant = -T / (ln(1 - filter))
 *
 *     T    - period at which the digital filter is being calculated
 *     f_in - input frequency of the filter
--- a/include/dspb16.h
+++ b/include/dspb16.h
@ -92,6 +92,7 @@
 *     filter = T * (2*PI) * f_c
 *
 *     phase shift = -arctan(f_in/f_c)
+ *     time constant = -T / (ln(1 - filter))
 *
 *     T    - period at which the digital filter is being calculated
 *     f_in - input frequency of the filter